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Vidna kognicija III

Vidna kognicija III. Danko Nikoli ć. Teme. Neurofiziološki kodovi prijenosa i obrade informacija u vidnom sustavu Dva kôda za percepciju svjetline Problem povezivanja dijelova vidne scene u cjelinu (tzv. binding problem ) Uloga pažnje u pohranjivanju informacija u radno pamćenje

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Vidna kognicija III

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  1. Vidna kognicija III Danko Nikolić

  2. Teme • Neurofiziološki kodovi prijenosa i obrade informacija u vidnom sustavu • Dva kôda za percepciju svjetline • Problem povezivanja dijelova vidne scene u cjelinu (tzv. binding problem) • Uloga pažnje u pohranjivanju informacija u radno pamćenje • Uloga radnog pamćenja za formiranje dugoročnog vidnog pamćenja • Mehanizmi sinestezijskih asocijacija

  3. New lectureSmall delays in synchronization

  4. → 150 ms → 250 ms

  5. The speed of vision Thorpe & Fabre-Thorpe (2001) 20 ms per stage! 1 spike per neuron! 40-50 ms 30-50 ms 20-40 ms 50-70 ms 70-90 ms 80-100 ms

  6. What can one spike tell us?

  7. What can one spike tell us?

  8. Kuffler (1953) Discharge patterns and functional organisation of vertebrate retina, Journal of Neurophysiology Increase in stimulus intensity Stimulus onset

  9. “I don’t think Steve much liked our abstract”.

  10. A simulation test Van Rulen and Thorpe (2001) Rate Coding Versus Temporal Order Coding:What the Retinal Ganglion Cells Tell the Visual Cortex, Neural Computation, 13

  11. Spike timing in sensory receptors

  12. Stimulus onset Onset latencies in somatosensation Johansson & Birznieks (2004) D1 D2 D3 D4 D5

  13. Measuring small delays • Fitting a function and taking its maximum value for the estimate. Cosine fit

  14. Phase offsets can be measured with sub-millisecond precision Schneider and Nikolić, Journal of Neuroscience Methods (2006).

  15. 200 μm 200 μm Large networks

  16. Relative firing time [ms]

  17. Relative firing time [ms] Extraction of the firing sequence Nikolić, Journal of Comp. Neuroscience (2007) Schneider, Havenith and Nikolić, Neural Computation (2006) Schneider and Nikolić, Journal of Neuroscience Methods (2006)

  18. Non-parametric detection of temporal order Nikolić, Journal of Comp. Neuroscience (2007).

  19. Example: Stimulus dependence 1) 2)

  20. Firing sequences change dynamically

  21. Spike timing in single neurons:Synaptic integration Rall (1964)

  22. Spike timing in single neurons:Synaptic integration Rall (1964)

  23. Spike timing in single neurons:Synaptic integration Rall (1964)

  24. Spike timing in single neurons:Synaptic integration Rall (1964)

  25. Spike timing in single neurons:Synaptic integration Rall (1964)

  26. Spike timing in single neurons:Synaptic integration Rall (1964)

  27. Spike timing in single neurons:Synaptic integration Rall (1964)

  28. Spike timing in single neurons:Synaptic integration Euler & Denk (2004) Stiefel & Sejnowski (2007)

  29. Conclusion: Firing sequences • Short time delays can serves as a code for carrying stimulus-related information that is as reliable as is the neuronal firing rate. • Stronger synchronization increases the reliability of the code.

  30. Good timing is everything

  31. Binding problem

  32. Perceptual integration and organization

  33. Hierarchical coding by extraction of feature combinations Grandmother cell

  34. Problems: combinatorial explosion and novel combinations Combinatorial explosion: There are many different grandmothers and each can be seen from many different perspectives. Novel combinations: Some grandmothers are seen for the first time. There is no chance to learn all the possible combination of features that make a grandmother.

  35. Perceptual organization through synchronization of action potentials

  36. Split bar experiment (Gray et. al, 1989)

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